Bro limsc pretty much summed up what I wanted to say.
I'm assuming you are already getting very used to the convenience of taking cabs, and it is starting to hurt you in your wallet? Sometimes, it just takes good time management and discipline, and the bus or the MRT will meet your needs just fine.
Quite some time back, I used to take cabs to work and back home. I was so used to this "convenience", that I took cabs everywhere I went, which really drained my income, till I told myself, enough was enough. I slept earlier at night to wake up earlier in the morning, and cycle to the nearest bus stop to take the bus to work. I found that I had more savings, and the extras could be used to buy more corals!
I'm not discouraging you from getting a car, by all means go ahead if you can afford it! Its just that sometimes, it is better to deal with underlying issues rather than seeking other means to negate it.
Cheers!